In lofting a golf ball out of a trouble spot, such as rough or a sand trap, it is customary to use an iron, sand wedge, or the like, with considerable mass in the head to provide the necessary inertia and overcome resistance. The ball is usually struck in a downward direction to impart a back spin to retard rolling on the green and is lofted out by continued motion of the club, the head usually striking the ground immediately after contacting the ball. When the leading edge of the head strikes the ground surface or cuts through grass, the sharp leading edge has a tendency to dig into the turf, greatly reducing the power of the blow and including the possibility of deflecting the club from the desired path.
Ribbing or corrugation of the lower surface of the head has been used to reduce contact area, but there is still a large surface which must be forced through obstacles and the results have not been very satisfactory.
A wood with a pronounced curvature in the sole has been developed for use in the rough or on the fairway, but does not have sufficient mass for good penetration. In weighting a wood the weight is usually centrally located behind the striking point and the weight distribution in the head is not particularly good. Additionally a wood with a sole shaped like a single keel of a boat has been produced. However, this has a sharp leading edge which encourages penetration and greatly reduces the continued power of the swing.